Observation and Analysis of Model Lipid Raft Deformation Dynamics Induced by Lipoprotein–Gold Nanorod-based Devices to Manipulate Phase Transition of Lipid Bilayer

Lipid rafts, which are complexes that form on cholesterol-rich areas of cell membranes, play key roles as gates for the distribution of information between the inner and outer spaces of living cells. The physical and biological properties of lipid rafts have been investigated, but the engineering of lipid rafts remains a difficult subject. We developed a lipoprotein–gold nanorod nanodevice to control the formation/deformation of model lipid rafts. The nanodevice attached to the liquid order (Lo) phase region, selectively removed cholesterol from the Lo domain, and induced the Lo-to-solid order (So) phase transition. In this study, we analyzed the phase transition induced by the nanodevice. We found that the domain boundary gradually collapsed and that a local two-phase mixture was induced. Local instability resulted in domain incursion into other domains, and protrusions were torn to form small domains with the characteristics of two phases. The two different domains grouped together to form a non-circular So domain on giant unilamellar vesicles. Close observation of the non-equilibrium process of phase transition may lead to the design of strategies for external lipid raft manipulation methodology using biological macromolecules and/or nanoparticles.